Ball and cup impactors for implanting a hip prosthesis

ABSTRACT

New surgical instruments and methods used to implant elements of a reverse hip prosthesis in a patient are described. The instruments are impactors which are struck with a hammer at their proximal ends after the instrument has been used to position the implant element in the patient. An acetabular cup impactor has inclination and anteversion rods which are used to position the acetabular cup optimally in the acetabulum. An acetabular ball impactor affixes the acetabular ball in the acetabular cup by means of a Morse taper. And a femoral cup impactor affixes the femoral cup in the femoral stem by means of a Morse taper.

This is a Divisional patent application of U.S. Ser. No. 15/742,252,which in turn is an application filed under 35 USC 371 based onPCT/US2016/042441 filed 15, Jul. 2016, which in turn claims priority toU.S. Ser. No. 62/197,215 filed 27, Jul. 2015. The present applicationclaims the full priority benefit of these prior applications andincorporates by reference the full disclosures of these priorapplications as if set forth herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to surgical instruments used in connectionwith implanting a reverse hip prosthesis in a patient. Moreparticularly, the invention has to do with impactors for implanting anacetabular cup, an acetabular ball and a femoral cup.

The Related Art

A reverse hip prosthesis is described in U.S. Pat. Nos. 8,313,531 B2 and8,540,779 B2. The prosthesis and a revision surgery method also aredescribed in U.S. Pat. No. 8,992,627 B2. The disclosures of these threepatents are incorporated herein in their entireties by reference.

SUMMARY OF THE INVENTION

As described in the patents referenced above, the acetabular cup isaffixed in the acetabulum by impacting it therein and then, if needed,affixing it further using screws. The acetabular ball is affixed bymeans of a Morse taper to a stem extending from the bottom of theconcave surface of the acetabular cup and the femoral cup is affixed tothe femoral implant (or femoral stem) by means of a Morse Taper. Thesurgical instruments of the invention, sometimes referred to herein assurgical tools, enable a surgeon to impact each of these components ofthe prosthesis with optimal placement of the acetabular cup and secureaffixation of the acetabular ball and the femoral cup.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the acetabular cup impactor assembly ofthe invention.

FIG. 2 is an elevation view of the acetabular cup impactor assembly.

FIG. 3 is a section view of FIG. 2 illustrating a partial acetabularbone element.

FIG. 4 is an exploded view of the acetabular cup impactor assembly.

FIG. 5 is an elevation view of an acetabular cup handle for theacetabular cup impactor assembly.

FIG. 6 is an elevation view of an inner shaft for the acetabular cupimpactor assembly.

FIG. 7 is an elevation view of an inclination-anteversion guide rod forthe acetabular cup impactor assembly.

FIG. 8 is an elevation view of a collet for the acetabular cup impactorassembly.

FIG. 9 is an elevation view of a universal handle for the acetabularball impactor assembly and the femoral cup impactor assembly.

FIG. 10 is a perspective view of an acetabular ball impactor assembly,acetabular ball and acetabular cup.

FIG. 11 is an elevation view of FIG. 10.

FIG. 12 is a section view of FIG. 11 with an added acetabular boneelement.

FIG. 13 is an elevation view of an acetabular ball impactor.

FIG. 13A is a section view of the acetabular ball impactor of FIG. 13.

FIG. 14 is an elevation view of a femoral cup impactor assembly.

FIG. 15 is a perspective view of a femoral cup impactor.

FIG. 16 is a side elevation view of FIG. 15.

FIG. 17 is a top elevation view of FIG. 16.

FIG. 18 is a bottom elevation view of FIG. 16.

FIG. 19 is an elevation view of a femoral cup impactor assembly and afemoral cup positioned in a femoral implant, the femoral implant beingillustrated in section.

FIG. 20 is a section view of FIG. 19.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The impactors of the present invention are used to implant in a patientthree elements of a reverse hip prosthesis. The elements are theacetabular cup, the acetabular ball and the femoral cup.

Following preparation of the acetabulum to receive the acetabular cup,the acetabular cup is positioned in the acetabulum and impacted thereinusing the acetabular cup impactor assembly 1 illustrated in FIGS. 1-4.Elements of acetabular cup impactor assembly 1 are illustrated in FIGS.5-8. FIGS. 1-3 illustrate acetabular cup 2 in relation to the assembly 1and FIG. 3 includes a portion of the acetabulum 3.

The acetabular cup impactor assembly 1 is comprised of acetabular cuphandle 4, having a channel extending annularly along the length thereof,the channel being open at the proximal and distal ends of the handle 4,inner shaft 5 having a knob 6 at the proximal end thereof,inclination-anteversion guide rods 7 and collet 8. Guide rods 7 arethreaded at their distal ends. The acetabular cup handle 4 has a handleshaft 9 and an inclination-anteversion guide collar 10 rotatably mountedon handle shaft 9. Inclination-anteversion guide collar 10, sometimesreferred to herein as rotatable guide 10, has threaded holes (See FIG.4.) designated as anteversion holes 15 and inclination hole 16. A rod 7is threaded into hole 16 and one of holes 15, depending on whether theright or left hip is being replaced. Thumb screw 11 is tightened toprevent rotation of guide collar 10 when a rod 7 is optimally positionedduring surgery. Handle element 12 is affixed proximally on shaft 9 andsleeve 13 is affixed to the distal end of shaft 9. The sleeve 13 has atapered annular inner portion, the taper narrowing in the proximaldirection, the tapered annular inner portion of the sleeve 13 beingsized to cause a distal end of the collet 8 to contract when the collet8 moves into the sleeve 13 in a proximal direction. FIG. 4 illustratesthree collets 8, each being of a different size for different sizes ofacetabular cups 2. Acetabular cup 2 has a stem 14 projecting from thebottom of the concave surface thereof. The size of the collet 8 refersto an annular inner portion thereof which is sized to releasably grip aproximal portion of the stem 14. The collet 8 grips the stem 14 when thecollet 8 is contracted and releases the stem 14 when the collet 8 isopen, i.e., not contracted.

In the surgical method of the invention, the acetabulum 3 is prepared toreceive an appropriately sized acetabular cup 2 and a collet 8 sized forthe cup is selected. Inner shaft 5 is inserted into the distal end ofacetabular cup handle 4 and the collet 8 is then attached to the distalend of inner shaft 5. The collet 8 is then pushed over the stem 14 ofacetabular cup 2 and the collet 8 is pulled into sleeve 13 so that thecollet 8 firmly grips the stem 14. This causes shaft 5 to moveproximally leaving a space between knob 6 and the proximal end of handleelement 12. An inclination-anteversion guide rod 7 is threaded into hole16 of inclination-anteversion guide collar 10, anotherinclination-anteversion guide rod 7 is threaded into a hole 15 (see FIG.4), and the acetabular cup 2 is placed in acetabulum 3. Then the screwholes in cup 2 are aligned properly in the acetabulum for eventualfixation of the cup to the acetabulum using screws. Theinclination-anteversion guide collar 10 is then rotated until the rods 7are properly positioned and thumb screw 11 then is tightened. It shouldbe noted that the guide rods are set at a 45 degree angle relative tothe shaft 9 and at a 20 degree angle relative to one another. Thesurgeon sets the inclination using the rod threaded into hole 16 bykeeping the rod parallel to the floor and pointing it toward theshoulder of the patient. If a left hip is being replaced it is pointedat the left shoulder and if a right hip is being replaced it is pointedat the right shoulder. When the inclination is set, the surgeon thensets the anteversion using the rod 7 threaded into a hole 15. Eitherhole 15 is used, depending on whether the right hip or left hip is beingreplaced as will be apparent to those having ordinary skill in the artbased on the disclosures herein. The anteversion rod creates 20 degreesof anteversion with the inclination rod by orienting the anteversion rodtoward the same shoulder. The rods are used in this manner with aposterior surgical approach and this properly sets the orientation ofthe cup 2 at a compound angle of 45 degrees of inclination and 20degrees of anteversion. The assembly is maintained in position byholding handle element 12 as the proximal end of knob 6 is struck with ahammer thereby impacting the acetabular cup in the acetabulum. Assembly1 is then removed from the operating site.

An acetabular ball impactor assembly is illustrated in FIGS. 10-12 andthe acetabular ball impactor 20 is illustrated in elevation in FIG. 13.The acetabular ball impactor assembly 13 is comprised of acetabular ballimpactor 20 and universal handle 40. (See also FIG. 9). The universalhandle 40 is comprised of shaft 41 having a threaded portion 42 at itsdistal end and a handle element 43 at its proximal end. The acetabularball impactor 20 has a proximal end and a distal end. As illustrated inFIG. 13A, the proximal end of acetabular ball impactor 20 has threads 22and the distal end has a concave surface portion 23. The concave surfaceportion being in the shape of a section of a sphere. The threadedportion 42 is threaded into the threads 22 of the acetabular ballimpactor 20.

Acetabular ball impactor 20 is made in sizes compatible with differentlysized acetabular balls 21. When a ball 21 is selected, it is placed overstem 14 of acetabular cup 2. The appropriately sized acetabular ballimpactor 20 is threaded onto the universal handle 40 and the concavesurface of acetabular ball impactor 20 is placed over the ball, allowingthe ball to be received therein. Appropriate sizing in this contextmeans the concave surface portion of the acetabular ball impactor issized to receive the acetabular ball. Thus the concave surface has theshape of a section of a sphere and a size the same as or approximatelythe same as the spherical size of the acetabular ball to be receivedtherein. With the universal handle 40 held in a position wherein thecentral axis of the stem 14 and the central axis of the shaft 41 are inthe same or approximately the same line (as illustrated in FIGS. 11 and12) the proximal end of handle element 43 is struck with a hammer tocause the acetabular ball 21 to be firmly affixed to stem 14 by means ofthe Morse taper.

A femoral cup impactor 30 is illustrated in FIGS. 15-18. It is comprisedof a convex surface portion, referred to herein as impactor tip 31, atits distal end and a threaded portion 32 at its proximal end. The convexsurface portion is in the shape of a sphere. Threaded portion 32 is usedto affix the impactor to universal handle 40. When the femoral cupimpactor 30 is affixed to universal handle 40, the combination ofelements is referred to herein as a femoral cup impactor assembly.

FIGS. 19 and 20 further illustrate the femoral cup impactor, a femoralcup 50 and a femoral implant 51. The femoral cup 50 has a stem 52 whichis sized to fit in a Morse taper relationship in recess 53 of femoralstem 51.

Femoral cup impactor 30 is made in sizes compatible with differentlysized femoral cups 50. The femoral cup 50 has a concave surface portionin the shape of a section of a sphere sized to articulate on acetabularball 21. When a femoral cup 50 is selected, the stem 52 is placed inrecess 53. The appropriately sized acetabular cup impactor is threadedonto the universal handle 40 and the convex impactor tip 31 is placedinto the concave portion of femoral cup 50. Appropriate sizing in thiscontext means the convex surface of the femoral cup impactor is sized tobe received in the concave surface portion of the femoral cup. Thus theconvex surface has the shape of a section of a sphere and a size thesame as or approximately the same as the concave surface portion of thefemoral cup. Thus the convex surface has the shape of a section of asphere and a size the same as or approximately the same as the concavesurface portion of the femoral cup. With the universal handle 40 held ina position wherein the central axis of the stem 52 and the central axisof the shaft 41 are in the same or approximately the same line (asillustrated in FIGS. 19 and 20) the proximal end of handle element 43 isstruck with a hammer to cause the femoral cup 50 to be firmly affixed tofemoral implant 51 by means of the Morse taper.

The surgical instruments of the invention may comprise a portion ofsurgical kits. The kits may contain one or more than one of the surgicalinstruments of the invention along with other surgical instrumentsand/or implants.

The invention claimed is:
 1. An acetabular ball impactor assembly havinga handle and and an acetabular ball impactor, the assembly configured toaffix an acetabular ball onto a stem of an implanted acetabular cupwhich has a concave inner surface with the stem extending from theconcave inner surface via impaction of the acetabular ball impactorcausing the acetabular ball to be affixed to a part of the stem, theacetabular cup being affixed to an acetabulum of a patient, wherein: thehandle comprises a solid shaft having a proximal end, a central axis,and a distal end, a threaded portion at the distal end and a handleelement at the proximal end, and the acetabular ball impactor comprisesa body with a proximal end and a distal end, threads disposed at theproximal end of the body, the threads sized to receive the threadedportion at the distal end of the shaft, and a circular concave surfaceextending inwardly from the distal end and into the body and anuninterrupted circumferential part defining a circumferential openinghaving a circular margin and a diameter approximately equal to or adiameter larger than a diameter of the circular concave surface, theuninterrupted circumferential part and the concave surface being sizedto receive the acetabular ball, and further wherein; a length of thebody between a point of the circular concave surface most proximate tothe proximal end and the circular margin of the uninterruptedcircumferential part is such that an entirety of the circular margin isspaced from the concave inner surface of the implanted acetabular cupwhen the acetabular ball is affixed to the stem, and the body has awidth which at a maximum dimension is smaller than a maximum width ofthe acetabular cup.
 2. A kit containing the acetabular ball impactorassembly of claim 1, and one or more further other surgical instrumentsand/or implants.
 3. The kit of claim 2, which further comprises asurgical instrument configured to impact an acetabular cup into anacetabulum of a patient wherein the acetabular cup has a central stemhaving a Morse taper extending from a bottom of a concave inner surfacethereof, the surgical instrument comprising: a handle having a proximalend and distal end and a central axis, a sleeve disposed on the distalend concentric with the handle of the surgical instrument and an annularchannel extending therethrough, the annular channel being open at theproximal and the distal ends of the handle of the surgical instrument, ashaft having a proximal end and a distal end and a knob affixed to theproximal end, the shaft of the surgical instrument being slidablydisposed within the annular channel, a collet removably affixed to thedistal end of the shaft of the surgical instrument and proximate thesleeve, wherein the sleeve has a tapered annular inner portion, thetapered annular inner portion narrowing in a proximal direction, thetapered annular inner portion of the sleeve being sized to cause adistal end of the collet to contract and grip the central stem of theacetabular cup and thereby gripping the acetabular cup only by thecentral stem when the collet moves into the sleeve in the proximaldirection, a rotatable guide collar mounted externally on the handle ofthe surgical instrument and rotatable about the central axis of thehandle of the surgical instrument configured to have affixed to therotatable guide collar a plurality of guide rods wherein each of theguide rods has a proximal end removably affixable to the rotatable guidecollar and extending outwardly therefrom at an angle relative to thecentral axis, wherein at least two of the guide rods, when affixed tothe rotatable guide collar are each positioned at a 45 degree anglerelative to the shaft of the surgical instrument, and are positioned ata 20 degree angle relative to each other, and the direction of the atleast two affixed guide rods are oriented to extend in a distaldirection from the rotatable guide collar and a thumb screw having apart extending into the rotatable guide collar wherein rotation of thethumb screw prevents movement of the rotatable guide collar and of anyof the guide rods affixed to the rotatable guide collar relative to thehandle of the surgical instrument.
 4. The kit of claim 3, wherein thecollet has a collet inner portion sized to releasably grip a proximalportion of the central stem, gripping the stem when the collet iscontracted and releasing the central stem when the collet is notcontracted.
 5. The kit of claim 3, which comprises a plurality ofcollets.
 6. The kit of claim 5, wherein at least two of the plurality ofcollets have different sizes.
 7. A method of using the acetabular ballimpactor assembly of claim 1, the method comprising: placing anacetabular ball onto a stem of an acetabular cup, positioning a concavesurface of the acetabular ball impactor on the acetabular ball, holdingthe handle in a position wherein a central axis of the stem and thecentral axis of the shaft are coincident or approximately coincident andthen, striking a proximal end of the handle element with a hammer tothereby affix the acetabular ball to a part of the stem extending fromthe concave inner surface but without contacting any part of thecircular margin with the concave inner surface of the implantedacetabular cup.
 8. The acetabular ball impactor assembly of claim 1,wherein the concave surface sized to receive the acetabular ball is inthe shape of a section of a sphere.